This invention relates generally to gas turbine engine bearing sumps and more particularly to fluid flow provisions in bearing sumps.
A gas turbine engine includes one or more shafts which are mounted for rotation in several bearings, usually of the rolling-element type. The bearings are enclosed in enclosures called “sumps” which are pressurized and provided with an oil flow for lubrication and cooling. In most cases one of the boundaries of the sump will be a dynamic seal between a rotating component of the engine and the engine's stationary structure. Various tubes, connectively referred to as “service tubes”, are used to supply oil to the sump, to drain spent oil from the sump, to pressurize the sump with air, and to vent air from the sump.
The bearings and sumps are mounted within a casing of the engine using stationary structural members commonly called frames, usually having a central hub connected to an annular outer rim with a plurality of radial struts. The above-mentioned service tubes frequently are routed through the struts. Some gas turbine engines incorporate a type of frame called a “turbine vane frame” or “TVF” instead of a traditional “turbine center frame” or “TCF”. A TVF has fewer struts than a TCF and those struts are usually thinner in cross-section than a comparable TCF. Utilizing a TVF rather than a TCF can enhance the engine's performance and reduce the overall engine weight.
The thinner and fewer struts of a TVF, while providing several advantages, also challenge the ability to route large oil supply, scavenge, drain and ventilation tubes to bearing sumps.
Accordingly, there is a need for a configuration for routing tubes within a gas turbine engine having limited frame strut area.